So-called "cold-strippers" are compositions that are effective at room temperature in removing paints and varnishes from surfaces that have been painted or varnished. These strippers are well-known in the art. By way of illustration, U.S. Pat. No. 2,507,984 discloses a stripping composition for stripping paint or varnish from surfaces of metal, wood, glass, fabrics or brushes consisting essentially of methylene chloride, water, and at least one acid selected from the group consisting of formic, acetic, propionic, salicylic, butyric, carbolic, benzoic and cinnamic acids. U.S. Pat. No. 2,507,985 discloses a stripping composition for stripping identical surfaces consisting essentially of formic acid, acetic acid, water, and a solvent selected from the group consisting of methylene chloride, ethylene dichloride, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, chloroform and ethylene chlorohydrin. As another example, U.S. Pat. No. 3,391,085 discloses a stripping solution for metal surfaces consisting essentially of methylene chloride, formic acid, phenol, water and p-toluenesulfonic acid. As yet another example, U.S. Pat. No. 3,432,347 discloses the room temperature stripping of polymer films from metallic substrates with a composition comprising anhydrous fluorosulfonic acid.
It has now been found that an improved aqueous cold stripper composition for metals comprising methylene chloride, formic acid, chlorinated acetic acid and a surfactant selected from the class consisting of sulfonated castor oil and alkylbenzene sulfonic acid, or salts thereof, wherein the alkyl group has from about 10 to about 14 carbon atoms, provides an excellent combination of low toxicity, as compared to fluorinated compounds such as the above-mentioned anhydrous fluorosulfonic acid, and improved stripping action.